1. Field of the Invention
The invention concerns a procedure and apparatus for bending of a glass pane, for example an automobile glass pane, with the assistance of a multipart bending form whose form parts are connected to one another, whereby a glass pane, heated to the bending temperature, is grasped by the bending form and, through horizontal sweeping at least of one form part around an articulated axis, the pane is bent into the desired form.
2. Discussion of the Background
A customary procedure for bending of glass panes involves shaping the glass panes, heated to bending temperature in vertical position, with the assistance of a bending press comprising two bending tools. A male mold-shaped bending tool is typically constructed as a rigid all-over bending form, and a female mold-shaped bending tool as a multipart frame bending form whose individual form sections are connected through joints with one another. For bending of the glass pane, horizontally-sweepable lateral form sections of the female mold, having shapes corresponding to the desired form of the glass pane, are moved into an open position, the glass pane is grasped with the middle form section and pressed against the male mold-type bending form, and subsequently the lateral form sections are moved into a closed position, whereby the lateral sections of the glass pane are pressed against the male mold-shaped bending form. At the closing of the "folding corners", the glass pane is pulled in with increasing shaping by the bent folding corners, whereby significant relative movement occurs between the glass pane and the form surface of the bending form. Such multipart bending forms in particular find application in bending of glass panes with severely bent or respectively angled side parts. For example, they find application as windshield panes or rear panes in motor vehicles.
There are also known and customary bending procedures in which the glass pane to be bent is bent while in horizontal position, both with the assistance of pressing tools and according to the so-called "skeleton bending procedure" due to flection of the heated glass pane under the effect of its own weight on a frame bending form. The applied frame bending forms, in the case of severe curvatures, comprise several form sections which are hingedly connected with one another, and which more during the bending process through horizontal sweeping around their articulated axes from the closed position into the open one.
Furthermore, there are known procedures for bending of glass panes in the horizontal position in which the glass pane is grasped by one of several suction plates lowerable onto the heated glass pane, the plates being collectively flexible, and which, after the grasping of the glass pane, are bent together with the pane into the desired form. Procedures of this type are described for example in DE-OS No. 31 09 149 and in FR-OS Nos. 25 46 505, 25 46 506 and 25 46 507.
In the case of all of these known bending procedures, there cannot be helped a more or less severe sliding relative movement between the surface of the glass and the form surface of the sweepable form sections in contact with the glass surface. This relative movement between the form surface and the glass pane leads, as a rule, to an impairment of the glass surface which can manifest itself in minor deviations from the desired contour of the glass pane at the edge region, in undesired elongations or upsetting deformations of the glass pane in regions with severe curvature, and/or in surface damage to the glass pane.